Mastering API 682

API 682 is a global adopted developed by the American Petroleum Institute that defines recommendations for the design, selection, testing and operation of mechanical seals and seal support systems for centrifugal and rotary pumps used mainly in oil and gas, and chemical industries.

API 682 standardises:

• Mechanical seal design categories
• Seal arrangements (single, dual-unpressurised, dual-pressurised)
• Seal chamber dimensions
• Piping plans (flush/support systems)
• Material selection
• Testing and qualification

API 610 covers pump design, while API 682 covers mechanical seals and seal support systems used on those pumps.

Key distinction:

Many projects require both standards together.

All mechanical seals allow some leakage across the seal faces.

Arrangement 3 seals are able to achieve zero-emissions to atmosphere during normal operation by employing a barrier fluid at higher pressure between the process and the atmosphere. This makes them the preferred solution for volatile or hazardous fluids.

These categories classify seal construction and service severity:

• Category 1 → General refinery service
• Category 2 → Higher reliability and instrumentation
• Category 3 → Severe service with highest robustness

Key updates include:

• New piping plans added (e.g., 03, 55, 65A, 65B, 66A, 66B)
• Instrument changed from switches to transmitters
• Floating alarm added for Plan 53B to track changing effect of temperature
• Improved standardisation of seal systems

Not legally mandatory — but often required by:

• Oil and gas operators
• EPC specifications
• Corporate engineering standards
• Insurance / risk management policies

• Oil and gas
• Petrochemical
• Refining
• Chemical processing
• LNG

Its adoption continues to grow outside refining due to reliability gains.